Answer:
3-ethylpentane.
Explanation:
Hello,
In this case, considering that an ethyl radical is required at the main chain the place at which it is considered a radical is at the third carbon of a pentane, which is named as 3-ethylpentane taking into account the attached picture. It is important to notice that if such ethyl was at a different carbon atom, name will be 3-methyl-hexane which is not as required.
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